This session will describe how two United States Department of Education Mathematics and Science Projects impacted elementary mathematics teachers’ content knowledge using differing delivery models. Each project taught content in these areas: number and operations, geometry, statistics and probability and algebra. Pre/post- test content test data findings along with delivery model design and implementation successes and pitfalls will be discussed. Implications for in-service and pre-service content and pedagogy courses and delivery models will be noted. Attendees will be asked to discuss how their professional development activities and courses are related to project findings and recommendations.